In situ ultrasonic flow meter validation

ABSTRACT

A method of in situ ultrasonic flow meter validation includes receiving data characterizing first signal diagnostics and data characterizing a first speed of a first acoustic signal through a gas mixture along a first path in a pipe. The first speed of the first acoustic signal is detected by a first channel of an ultrasonic flow meter including a first pair of transducers that are separated by a first path length of the first path. The gas mixture is configured to flow along a flow path in the pipe. The method also includes determining a status associated with the ultrasonic flow meter based on the data characterizing the first signal diagnostics and/or a difference between the first speed of the first acoustic signal and an independently calculated speed of sound. The speed of sound is calculated based on one or more properties of the gas mixture.

BACKGROUND

Ultrasonic measurement systems can be used to determine properties of afluid flowing through a conduit (e.g., pipe). These systems can operateby creating an acoustic signal pulse, and transmitting the pulse througha fluid in a conduit, and receiving the signal after it has traveledalong a path in the fluid. Two or more independent paths may be used(e.g., orthogonal mid-radius paths, or clockwise and counterclockwisepaths) to transmit and receive acoustic pulses that can be indicative ofsound speed, or of directional fluid flow rate. Important properties ofthe fluid can be determined as a function of the transit times of theacoustic signals.

It can be desirable to detect properties of fluid generated in anindustrial process. For example, it can be desirable to determine theenergy content or British thermal unit (BTU) value of a flare gas thatcan be indicative of combustion efficiency of the flare gas. Forexample, the U.S. Environmental Protection Agency (EPA) regulations canstipulate that the combustion efficiency of flare gas is periodicallydetected and shown to have a value in a desirable range. Combustionefficiency of the flare gas can be determined, for example, based oncomposition of the flare gas that can be measured by a gas analyzer(e.g., gas chromatograph or mass spectrometer). Alternately oradditionally, combustion efficiency of the flare gas can be calculatedfrom the speed of sound (e.g., an acoustic signal) in the flare gas.

SUMMARY

Various aspects of the disclosed subject matter may provide one or moreof the following capabilities. The in situ ultrasonic flow metervalidation system can allow for an automatic diagnostic test of anultrasonic flow meter and verify its accuracy. In some implementations,the automatic diagnostic test can determine that the flow meter requiresmaintenance (e.g., flow meter path needs to be readjusted or transducersneed to be checked) and can notify maintenance personnel. In someimplementations, the automatic diagnostic test can determine that anundesirable operation of the flow meter can be resolved in situ (e.g.,without the removal of the flow meter from a pipe), and can recalibratethe flow meter. The in situ ultrasonic flow meter validation system canenable end users to meet compliance requirements, reduce unnecessarydowntime and reduce operational costs. It can allow for tracking theoperation of the flow meter over a period of time that can allow forfaster maintenance and timely replacement of the flow meter.

A method of in situ ultrasonic flow meter validation includes receivingdata characterizing first signal diagnostics and data characterizing afirst speed of a first acoustic signal through a gas mixture along afirst path in a pipe. The first speed of the first acoustic signal isdetected by a first channel of an ultrasonic flow meter including afirst pair of transducers that are separated by a first path length ofthe first path. The gas mixture is configured to flow along a flow pathin the pipe. The method also includes determining a status associatedwith the ultrasonic flow meter based on the data characterizing thefirst signal diagnostics and/or a difference between the first speed ofthe first acoustic signal and a calculated speed of sound. The speed ofsound is calculated based on one or more properties of the gas mixture.The method further includes providing a notification including thedetermined status to a user and/or saving the notification to anelectronic storage.

One or more of the following features can be included in any feasiblecombination.

In one implementation, the method further includes receiving datacharacterizing one or more properties of the gas mixture. The one ormore properties includes one or more of composition of the gas mixture,pressure of the gas mixture in the ultrasonic flow meter, andtemperature of the gas mixture; and calculating, using a predeterminedalgorithm, the speed of sound based on the data characterizing the oneor more properties of the gas mixture. In another implementation, thepredetermined algorithm includes one or more of a molecular-weight basedalgorithm, an AGA10 method and an ideal gas law. In yet anotherimplementation, the status includes an identity of the ultrasonic flowmeter.

In one implementation, the data characterizing the first signaldiagnostics includes one or more of the first path length, time delay ofa first transducer and/or a second transducer of the first pair oftransducers and a signal strength, and a signal-to-noise ratio. The datacharacterizing the first speed of the first acoustic signal includes afirst upstream time of travel of sound from the first transducer to thesecond transducer, and a first downstream time of travel of sound fromthe second transducer to the first transducer.

In one implementation, the method further includes receiving datacharacterizing second signal diagnostics and data characterizing asecond speed of a second acoustic signal through a gas mixture along asecond path in the pipe. The second speed of the second acoustic signalis detected by a second channel of the ultrasonic flow meter including asecond pair of transducers that are separated by a second path length ofthe second path. The data characterizing the second signal diagnosticsincludes one or more of the second path length, time delay of a thirdtransducer and/or a fourth transducer of the second pair of transducers,a signal strength and a signal-to-noise ratio. The data characterizingthe second speed of the second acoustic signal includes a secondupstream time of travel of sound from the third transducer to the fourthtransducer, and a second downstream time of travel of sound from thefourth transducer to the third transducer.

In one implementation, determining the status includes determining thatone or more of the first signal diagnostics of the first acoustic signalhas a first predetermined value, the second signal diagnostics of thesecond acoustic signal has a second predetermined value, the differencebetween the first speed of the first acoustic signal and the calculatedspeed of sound is above a higher threshold value, and a differencebetween the second speed of the second acoustic signal and thecalculated speed of sound is above the higher threshold value.Determining the status further includes setting the status associatedwith the ultrasonic flow meter to indicate a maintenance request.

In one implementation, determining the status includes determining thatone or more of the first signal diagnostics of the first acoustic signalhas a first predetermined value, the second signal diagnostics of thesecond acoustic signal has a second predetermined value, the differencebetween the first speed of the first acoustic signal and the calculatedspeed of sound is below a higher threshold value and above a lowerthreshold value, and a difference between the second speed of the secondacoustic signal and the calculated speed of sound is below the higherthreshold value and above the lower threshold value. Determining thestatus further includes setting the status associated with theultrasonic flow meter to indicate that the ultrasonic flow meterrequires calibration. In another implementation, the method furtherincludes calibrating the ultrasonic flow meter by varying one or more oftime delay of the first transducer and/or the second transducer, thefirst path length, time delay of the third transducer and/or the fourthtransducer, and the second path length.

In one implementation, determining the status includes determining thatone or more of the first signal diagnostics of the first acoustic signalhas a predetermined value, the difference between the first speed of thefirst acoustic signal and the calculated speed of sound is below a lowerthreshold value, and a difference between the second speed of the secondacoustic signal and the calculated speed of sound is below the lowerthreshold value. Determining the status further includes setting thestatus associated with the ultrasonic flow meter to indicate that theultrasonic flow meter performance has been validated.

In one implementation, determining the status includes calculating afirst velocity of fluid flow based on time difference between the firstupstream time of travel and the first downstream time of travel.Determining the status also includes calculating a second velocity offluid flow based on time difference between the second upstream time oftravel and the second downstream time of travel. Determining the statusfurther includes calculating a difference between the first fluidvelocity and the second fluid velocity is above a higher thresholdvalue; and setting the status associated with the ultrasonic flow meterto indicate a maintenance request.

In one implementation, determining the status includes calculating afirst velocity of fluid flow based on time difference between the firstupstream time of travel and the first downstream time of travel.Determining the status also includes calculating a second velocity offluid flow based on time difference between the second upstream time oftravel and the second downstream time of travel. Determining the statusfurther includes calculating a difference between the first fluidvelocity and the second fluid velocity is below a lower threshold value;and setting the status associated with the ultrasonic flow meter toindicate a successful in situ validation. In another implementation, thenotification includes the determined status in a flare application orindustrial process application.

Non-transitory computer program products (i.e., physically embodiedcomputer program products) are also described that store instructions,which when executed by one or more data processors of one or morecomputing systems, causes at least one data processor to performoperations herein. Similarly, computer systems are also described thatmay include one or more data processors and memory coupled to the one ormore data processors. The memory may temporarily or permanently storeinstructions that cause at least one processor to perform one or more ofthe operations described herein. In addition, methods can be implementedby one or more data processors either within a single computing systemor distributed among two or more computing systems. Such computingsystems can be connected and can exchange data and/or commands or otherinstructions or the like via one or more connections, including aconnection over a network (e.g. the Internet, a wireless wide areanetwork, a local area network, a wide area network, a wired network, orthe like), via a direct connection between one or more of the multiplecomputing systems, etc.

These and other capabilities of the disclosed subject matter will bemore fully understood after a review of the following figures, detaileddescription, and claims.

BRIEF DESCRIPTION OF THE FIGURES

These and other features will be more readily understood from thefollowing detailed description taken in conjunction with theaccompanying drawings, in which:

FIG. 1 is a flow chart of an exemplary method for in situ ultrasonicflow meter validation;

FIG. 2 is a schematic illustration of an exemplary in situ validationsystem;

FIG. 3 is an illustration of an exemplary flow meter having a singlechannel coupled to a pipe;

FIG. 4 is an illustration of another exemplary flow meter coupled to apipe; and

FIG. 5 is an illustration of an exemplary validation system with a flowmeter having two channels coupled to a pipe.

DETAILED DESCRIPTION

Industrial processes can generate one or more fluids (e.g., as aby-product or waste). It can be desirable to determine the compositionof the generated fluids. For example, generation and environmentaldisposition of flare gas (which can be generated during oil and naturalgas production) may need to be regulated to ensure that the compositionof the flare emissions complies with industry standards (e.g., EPAregulations). An ultrasonic flow meter can determine the speed of soundthrough a fluid (e.g., flare gas) in an industrial machine/pipeline. Thespeed of sound can be used to determine properties (e.g., composition,flow velocity, etc.) of the fluid. Speed of sound measurements can bevalidated via ex situ methods that require uninstalling the flow meter(or transducers therein) from the industrial machine/pipeline. This canrequire making provisions for access to maintenance personnel inhazardous areas and cause machine/pipeline down time which can result inloss of productivity. Furthermore, calibration of transducers underactual process conditions of fluid composition, pressure and temperaturemay be difficult to accomplish in an ex situ validation system, whichcan limit the accuracy of the latter. Accordingly, in situ ultrasonicflow meter validation systems and corresponding methods are providedthat can validate the operation of the ultrasonic flow meter withoutuninstalling it from the industrial machine/pipeline.

The flow meter can include one or more transducers that cangenerate/receive acoustic signals that can travel through a volume offluid in an industrial machine. In some implementations, the speed ofsound can be detected based on the time taken by acoustic signals totraverse a known path length in the fluid. The path length can be set toa predetermined value at the time of installation of the flow meter(e.g., installation on a pipe), which can be stored in a computingdevice. The path length can vary over time (e.g., due to stress/strainon the flow meter, change in temperature, error in installation, etc.),which can lead to an error in the determination of speed of sound. Timetaken by an acoustic signal to traverse the path length can depend onthe flow of the fluid (e.g., average flow of the fluid in the pipe).Acoustic signals traveling along different paths (e.g., paths that havedifferent orientation with respect to the direction of fluid flow) canhave different traversal times. For example, an acoustic signaltraveling along the direction of the fluid flow will traverse a givendistance faster than if it were traveling against the fluid flowdirection.

Transducer time delay (Tw) can be another factor that may be consideredduring in situ validation. Tw can be determined in the factory and itcan be unique for each transducer. Tw can be affected by temperatureand/or build-up of impurities on transducer surface in the pipeline. Therelationship between Tw and temperature can depend on transducer type.Sometimes, Tw may need to be adjusted in the field during flow metervalidation if path length is known (e.g., confirmed).

The in situ ultrasonic flow meter validation system can executediagnostic tests to detect a change in the path length of flow meter.This can be done by comparing the speed of sound detected by the flowmeter and a speed of sound calculated based on properties of the fluid(e.g., composition of the fluid, pressure exerted by the fluid near theflow meter, temperature of the fluid, and the like). In someimplementations, the validation system can notify a designated personnelthat the flow meter requires maintenance (e.g., when the differencebetween the detected and calculated sound speeds is greater than athreshold value). Based on the notification (e.g., a message sent to thedesignated personnel's computing device), the designated personnel canaddress the maintenance request. In some implementations, the validationsystem can execute corrective measures to identify and addressundesirable operation of the flow meter (e.g., change in the path lengthand/or transducer time delay (Tw)). For example, the validation systemcan execute diagnostic tests on the electronic components (e.g.,transducers) of the flow meter and modify the operation of theelectronic components, such as transducer time delay (Tw). In someimplementations, the validation system can also adjust the path lengthparameter of the flow meter if the path length changes from apredetermined value (e.g., when the difference between the path lengthand a predetermined value exceeds a threshold value). The validationsystem can generate a report of the diagnostic tests and provide thereport to an operator and save the report to a data storage device forrecord keeping. Alternately, the validation system can generate anotification that indicates that the flow meter is operating as desired(e.g., when the difference between the detected and calculated speeds issmaller than a threshold value).

FIG. 1 is a flow chart of an exemplary method for in situ ultrasonicflow meter validation. At 102, data characterizing a first speed ofacoustic signal and/or its diagnostics through a gas mixture along afirst path in a pipe can be received (e.g., by a computing device). Thefirst speed of acoustic signal can be measured by a first channel of aflow meter coupled to the pipe that can include a pair of transducersseparated by a pre-determined path length. The first channel can bearranged along the first path and the gas mixture in the pipe can flowalong a flow path. The first path of the acoustic signal and the flowpath can be oriented at an angle or can be parallel relative to eachother. FIG. 2 is a schematic illustration of an exemplary in situvalidation system 200 that can include a flow meter 202 configured todetect the first speed of acoustic signal through a gas mixture flowingthrough the pipe 250. The in situ validation system 200 can include acomputing device 204 that can receive data characterizing the detectedfirst speed of acoustic signal.

FIG. 3 illustrates an exemplary flow meter 300 coupled to a pipe 350.The flow meter 300 can include a first channel with a pair oftransducers 302 and 304 that can be separated by a path length P thatcan extend across the pipe (e.g., across the diameter of the pipe). Afluid (e.g., a gas mixture) can flow through the pipe 350 along a flowpath 310. The transducers 302 and 304 can be configured to transmitand/or receive an acoustic signal (e.g., an acoustic pulse). The flowmeter can include a detection system that can measure the time taken foran acoustic signal (or a sound wave) to travel along the path length P(e.g., from transducer 302 to transducer 304, or vice-versa). The timeof travel of the acoustic signal can depend on the velocity of fluidflow along the flow path 310. For example, the time of travel of soundwaves along an upstream direction (e.g., against the flow of fluid fromtransducer 304 to transducer 302) can be larger than the time of travelof sound wave along a downstream direction (e.g., along the flow offluid from transducer 302 to transducer 304). Based on the time oftravel (e.g., upstream travel time, downstream travel time, etc.) andthe path length between the transducers, the first speed of acousticsignal can be determined. The path length can be predetermined (e.g.,can be set to predetermined value when the flow meter is installed onthe pipe 350). However, the path length can vary (e.g., due tostress/strain on the flow meter, change in temperature, error ininstallation, etc.). This can lead to an error in the determination ofthe speed of acoustic signal (e.g., first speed of acoustic signal).Transducer time delay (Tw) can be set to a predetermined value. Tw canchange (e.g., due to temperature change and/or human error) and may needto be adjusted. The gas mixture can flow through the pipe 350. In someimplementations, data characterizing the first speed received by thecomputing device (e.g., computing device 204) can include the pathlength (e.g., path length P), time of travel of the acoustic signalalong the path length, and the like.

FIG. 4 illustrates another implementation of the flowmeter 400. In thisimplementation, transducer mounting fixtures are installed on top of thepipe, and the transducers 402 and 404 are turned 90 degrees inside thepipe facing each other. This configuration offers the flexibility ofimplementing different path lengths for the same pipe. Thisconfiguration can be needed for larger pipe sizes or for measuring flowof fluids with large attenuation of acoustic signal transmission becausethe path length could be too long for the exemplary flow meter 300described FIG. 3.

In some implementations, the ultrasonic flow meter can include twochannels where each of the two channels can independently transmit anddetect acoustic signals. It can be desirable to include two channels asit can allow for more accurate detection of flow of fluid (e.g.,effective fluid velocity along the fluid path) in the pipe. Time takenby an acoustic signal to travel through a flowing fluid can vary basedon the velocity of the fluid flow relative to the direction of travel ofthe acoustic signal. For a given channel, the time taken by the acousticsignal to travel upstream (e.g., from transducer 304 to transducer 302)can be different from the time taken to travel downstream (e.g., fromtransducer 302 to transducer 304). Alternately, time of travel ofacoustic signal can vary between channels depending on the path lengthand the profile of the fluid velocity within the pipe.

Determining the flow of fluid (e.g., fluid velocity) can improve thevalidation of the ultrasonic flow meter (e.g., measurement accuracy).For example, it can be desirable to prevent the flow of fluid in thepipe from exceeding a threshold value. Ultrasonic flow meters with twochannels can allow for more accurate detection of the flow of fluidwhich can result in improved monitoring of the industrial process by theultrasonic flow meter. In some implementations, each of the two channelscan detect the velocity of fluid flow (e.g., average fluid velocityacross a cross-section of the pipe) based on difference between upstreamand downstream travel time of the acoustic signal. If the differencebetween the velocities of fluid flow detected by the two channels isbelow a threshold value, measurements by the ultrasonic flow meter canbe deemed acceptable. Additionally or alternately, two or more channelscan improve the robustness of the ultrasonic flow meter (which can bedesirable for critical applications), reduce measurement uncertainties(e.g., by improving time resolution of acoustic signal detection),reduce uncertainty in determination of asymmetric flow profile of thefluid, etc.

FIG. 5 is an illustration of an exemplary validation system 500including a flow meter 502 having two channels and an analysis system506. The flow meter 502 and the analysis system 506 can be coupled to apipe 550. The pipe 550 can include a fluid flowing along the flow path510. The flow meter 500 can include a first channel with a pair oftransducers 512 and 514 that can be separated by a first path (havingpath length Q1) and a second channel with a pair of transducers 516 and518 that can be separated by a second path (having path length Q2). Thetransducers 512, 514, 516 and 518 can be in communication with acomputing device 504 (e.g., can transmit the time oftransmission/detection of acoustic signals). For each channel, theupstream and the downstream traversal times can be detected.Upstream/downstream velocity can be determined by dividing the pathlength with the upstream/downstream traversal time. The fluid velocitycan be determined from the difference between the upstream anddownstream velocities. For example, fluid velocity can be calculated foreach of the two channels. The computing device 504 can receive datacharacterizing the speed of acoustic signal in the first and secondchannels (e.g., upstream/downstream time of travel of sound waves alongthe first and second paths) and its signal diagnostic (e.g.,first/second path length, time delay of transducers 512, 514, 516, 518,etc.).

The in situ validation system 200 (or 500) can also include a gasmixture analyzer (“analysis system”) 206 (or analysis system 506) thatcan measure various properties of the gas mixture in the pipe 250 (orpipe 550) and provide information related to the measured properties tothe computing device 204 (or computing device 504). For example, theanalysis system 206/506 can include a gas analyzer (e.g., gaschromatograph, mass spectrometer, etc.) that can detect the compositionof the gas mixture in the pipe 250/550. The analysis system can includea pressure detector and/or a temperature detector that can measure thepressure and temperature of the gas mixture, respectively. The analysissystem 206/506 can transmit data characterizing one or more propertiesof the gas mixture (e.g., composition/pressure/temperature of the gasmixture) to the computing device 204/504. The computing device 204/504can receive the data and calculate the speed of sound in the gas mixture(e.g., in gas mixture independent of its flow rate) based on thereceived data. The speed of sound can be calculated using apredetermined algorithm.

In some implementations, the predetermined algorithm can receive datacharacterizing one or more properties of the gas mixture, and can outputthe second speed of acoustic signal. The predetermined algorithm caninclude a molecular-weight based algorithm (e.g., as described in U.S.Pat. No. 6,216,091). The molecular-weight based algorithm can be basedon a database of constants of hydrocarbon mixtures as a function ofaverage molecular weight of the hydrocarbon mixture. Themolecular-weight based algorithm can be configured to iteratively set ahypothetical molecular weight, determine the corresponding criticalproperties, and compute a predicted sound speed. If the two speedsdiffer, a new weight is set and the procedure is repeated until thepredicted sound speed matches the measured speed, indicating that thecurrent estimate is the correct average molecular weight.

The predetermined algorithm can include an AGA10 method and/or Ideal GasLaw. AGA10 can be used for hydrocarbons in the natural gas industry(e.g., from alkane group (C—C), such as methane or ethane). AGA10 cantake alkane gas compositions as inputs. Flare gases are products ofvarious chemical processes in refineries and petrochemical plants andtheir compositions can be very complex. Besides gases from the alkanegroup, flare gas can include gases from the alkene group (C═C), such asethylene or propylene. In some implementations, the molecular-weightbased algorithm is a preferred algorithm for flare application becauseit can cover a much wider range of gases. The Ideal Gas Law can be usedwhen process pressure is very close to ambient pressure. In someimplementations, at higher pressure, sound speed calculated using IdealGas Law yields higher error. For example, at 10 PSIG pressure, soundspeed error using Ideal Gas Law can be +/−1% for some gases, which is asizeable fraction of the ultrasonic flow meter accuracy for ultrasonicflow meter validation purpose.

Returning to FIG. 1, at 104, the computing device 204/504 can determinea status associated with the flow meter (e.g., flow meter 202, 502,etc.) based on signal diagnostics of the first acoustic signal and/or adifference between the first speed of acoustic signal and the calculatedspeed of sound. In some implementations, the status can indicate thatthe flow meter requires maintenance (e.g., the path length of the flowmeter needs to be adjusted and/or transducers need to be checked). Thiscan be done, for example, when signal diagnostics of the first acousticsignal are not acceptable (e.g., signal diagnostics do not have apredetermined value/range of values) and the difference between thefirst speed of acoustic signal and the calculated speed of sound (e.g.,absolute value of the difference) is above a higher threshold value. Forvalidation system 500, the computing device 504 can calculate a firstspeed difference between the speed of acoustic signal in the firstchannel and the calculated speed of sound, and a second speed differencebetween the speed of acoustic signal in the second channel and thecalculated speed of sound. The status of the flow meter 504 can be basedone or both of the calculated differences (e.g., when one or both of thecalculated speed differences is above the higher threshold value). Thehigher threshold value can be predetermined (e.g., programmed into thecomputing device 204 by a personnel). A lower threshold value can bepre-defined (e.g., based on flow meter 202 characteristics, when errorin the flow reading is due to sound speed error, etc). Lower thresholdcan be determined from flow meter 202 configuration and installationtolerance.

In some implementations, if signal diagnostics of the first acousticsignal are acceptable (e.g., signal diagnostics have a predeterminedvalue/range of values) and the difference between the first speed ofacoustic signal and the calculated speed of sound (or the first speeddifference and/or the second speed difference in the two channels offlow meter 502) is below the lower threshold, validation is considered apass and no adjustment is required. If signal diagnostics of the firstacoustic signal are acceptable (e.g., signal diagnostics have apredetermined value/range of values) and/or the difference between thefirst speed and calculated speed of sound (or the first speed differenceand/or the second speed difference in the two channels of flow meter502) is between the lower threshold and the higher threshold, thecomputing device 204 (or 504) can send a signal to flow meter 202 (or502) to perform an in situ sound speed calibration by adjusting eithertransducer time delay (Tw) or path length of the flowmeter. Thetransducer delay time can be associated with the transducers 302, 304,512, 514, 516, 518, etc. After in situ calibration, corrected soundspeed from flow meter 202 (or 502) can be validated and recorded. If thedifference is higher than the higher threshold, a “maintenance required”message can be sent to the user computing device 208 (or 508) for humanintervention. For example, in situ calibration can be done by changingthe pre-programmed path length or the transducer time delay (Tw) in theflow meter 202 (or 502). If the physical path length needs to beadjusted, “maintenance required” notification can be sent for humanintervention.

In some implementations, the status can indicate that the flow meter isnot operating as desired (e.g., sub-optimal operation) and/or anautomatic diagnostic test is being performed or will be performed tocalibrate the flow meter. This can be done, for example, when thedifference (e.g., absolute difference) between the first speed ofacoustic signal and calculated speed of sound (or the first speeddifference and/or the second speed difference in the two channels offlow meter 502) lies in a predetermined range of values (e.g., betweenthe lower threshold value and the higher threshold value). The computingdevice 204 (or 504) can execute one or more diagnostic tests when thedifference in speed of the first acoustic signal and speed of sound liesin the predetermined range. For example, the computing device 204 (or504) can execute a diagnostic test that can determine that thetransducers in the flow meter are operating as desired. For some typesof transducers, an echo self-diagnostic test can be performed tovalidate the transducer's performance. The instructions for thediagnostic test can be predetermined and can be stored in a storagedevice on the computing device 204 (or 504).

In some implementations, the computing device 204 (or 504) can vary thepath length by varying the location/orientation of or more transducersin the flow meter. For example, the transducers (e.g., transducers 302,304, 512, 514, 516, 518, etc.) can be mounted on actuators that can becontrolled by the computing device 204 (or 504). The computing device204 (or 504) can transmit a control signal to the actuator tomove/re-orient the transducers. In some implementations, the controldevice 204 (or 504) can send a control signal to alter the operation ofthe transducers. For example, transducer operation can be improved(e.g., optimized) to maximize signal transmission. Computing device 204(or 504) can estimate signal attenuation for any gas composition inputfrom the analysis system 206 (or 506) and adjust the center frequency ofthe transmitted acoustic signal accordingly. By lowering transmittedsignal frequency, transmission efficiency and signal amplitude can beimproved for high attenuation gases, such as hydrogen or carbon dioxide.For low attenuation gases, such as heavy hydrocarbons at higherpressure, time resolution and measurement precision can be improved byraising transmitted signal frequency. Transmitted power intensity canalso be altered to maximize signal amplitude when concentrations ofgases with different attenuations change. Transducer signal shape andsignal averaging can be improved (e.g., optimized) to improve signalquality.

In some implementations, the computing device 204 (or 504) caniteratively adjust the path length. For example, the computing device204 (or 504) can change the path length (e.g., P, Q1, Q2, etc.) afterdetecting signal diagnostics of the first acoustic signal and/or secondacoustic signal are acceptable (e.g., signal diagnostics do not have apredetermined value/range of values) and/or after comparing the firstspeed of the first acoustic signal and/or second acoustic signal withthe calculated speed of sound. After the path length has been changed,the measurement and comparison steps can be repeated, which in turn canbe followed by re-adjustment of the path length. These steps can berepeated until the difference between the speed of the first acousticsignal and the speed of sound is below a threshold value. The thresholdvalues described above (e.g., higher threshold value, lower thresholdvalue, etc.) can be depend on the velocity of fluid flowing throwing thepipe 250. For example, as the velocity of the fluid increases, thehigher threshold value can increase, and the lower threshold value candecrease.

Returning to FIG. 1, at 106, a notification can be provided to the user(e.g., by the computing device 204) and/or saved to a data storagedevice. The notification can include the determined status of the flowmeter (e.g., as described in step 104). The notification can be providedto a user-computing device 208 (e.g., cell phone, tablet, computeretc.). In some implementations, the notification can be curated fortransmission at a later time. In some implementations, the status canindicate that the flow meter is operating as desired (e.g., when thedifference between the speed of the first acoustic signal and thecalculated speed of sound is below the lower threshold value). Thenotification can include the time of status determination, an identityof the flow meter (e.g., identity number associated with the flowmeter), and the like.

The status can indicate that the flow meter requires maintenance (e.g.,when signal diagnostics of the first acoustic signal are not acceptable(e.g., signal diagnostics do not have a predetermined value/range ofvalues) and/or the difference between the speed of the first acousticsignal and the calculated speed of sound (or the first speed differenceand/or the second speed difference in the two channels of flow meter502) is above the upper threshold value. The notification can include areport having results of one or more diagnostic tests performed on theflow meter (e.g., defective transducer from an echo self-diagnostictest). The notification can also include the level of urgency associatedwith the maintenance request (e.g., high priority, low priority, etc.),previous maintenance work performed on the flow meter (e.g., time ofprevious maintenance, ID of personnel who performed the previousmaintenance, etc.), and the like.

The status can indicate that the flow meter is not operating as desired(e.g., sub-optimal operation) and/or an automatic diagnostic test isbeing performed or will be performed to calibrate the flow meter (e.g.when signal diagnostics of the first acoustic signal are acceptable andthe difference between the speed of the first acoustic signal and thecalculated speed of sound [or the first speed difference and/or thesecond speed difference in the two channels of flow meter 502] isbetween the upper and lower threshold value). The notification caninclude the diagnostic steps taken/will be taken by the computing deviceto address an issue associated with the flow meter. The notification caninclude a diagnostic report on the electronics in the flow meter (e.g.,transducer health). The notification can include differences between thespeed of the first acoustic signal and the calculated speed of soundbefore and after the in situ calibration.

In some implementations, the status of the flow meter 502 can bedetermined by the computing device 504 based on the difference betweenthe upstream and downstream time of travel (e.g., in the first channel,second channel, etc.), which in turn determines the fluid velocity. Forexample, the computing device 504 can calculate a first fluid velocitybased on the time difference between the first upstream time of traveland the first downstream time of travel, and calculate a second fluidvelocity based on the time difference between the second upstream timeof travel and the second downstream time of travel. The computing device504 can calculate a difference between the first fluid velocity and thesecond fluid velocity and determine if it is above a pre-determinedthreshold value. This threshold value can depend on the geometricconfiguration of the two channels/paths being compared. If thisdifference is above a threshold value (e.g., higher threshold value),the status of the flow meter 502 can be set to indicate a maintenancerequest.

Certain exemplary embodiments will now be described to provide anoverall understanding of the principles of the structure, function,manufacture, and use of the systems, devices, and methods disclosedherein. One or more examples of these embodiments are illustrated in theaccompanying drawings. Those skilled in the art will understand that thesystems, devices, and methods specifically described herein andillustrated in the accompanying drawings are non-limiting exemplaryembodiments and that the scope of the present invention is definedsolely by the claims. The features illustrated or described inconnection with one exemplary embodiment may be combined with thefeatures of other embodiments. Such modifications and variations areintended to be included within the scope of the present invention.Further, in the present disclosure, like-named components of theembodiments generally have similar features, and thus within aparticular embodiment, each feature of each like-named component is notnecessarily fully elaborated upon.

The subject matter described herein can be implemented in digitalelectronic circuitry, or in computer software, firmware, or hardware,including the structural means disclosed in this specification andstructural equivalents thereof, or in combinations of them. The subjectmatter described herein can be implemented as one or more computerprogram products, such as one or more computer programs tangiblyembodied in an information carrier (e.g., in a machine-readable storagedevice), or embodied in a propagated signal, for execution by, or tocontrol the operation of, data processing apparatus (e.g., aprogrammable processor, a computer, or multiple computers). A computerprogram (also known as a program, software, software application, orcode) can be written in any form of programming language, includingcompiled or interpreted languages, and it can be deployed in any form,including as a stand-alone program or as a module, component,subroutine, or other unit suitable for use in a computing environment. Acomputer program does not necessarily correspond to a file. A programcan be stored in a portion of a file that holds other programs or data,in a single file dedicated to the program in question, or in multiplecoordinated files (e.g., files that store one or more modules,sub-programs, or portions of code). A computer program can be deployedto be executed on one computer or on multiple computers at one site ordistributed across multiple sites and interconnected by a communicationnetwork.

The processes and logic flows described in this specification, includingthe method steps of the subject matter described herein, can beperformed by one or more programmable processors executing one or morecomputer programs to perform functions of the subject matter describedherein by operating on input data and generating output. The processesand logic flows can also be performed by, and apparatus of the subjectmatter described herein can be implemented as, special purpose logiccircuitry, e.g., an FPGA (field programmable gate array) or an ASIC(application-specific integrated circuit).

Processors suitable for the execution of a computer program include, byway of example, both general and special purpose microprocessors, andany one or more processor of any kind of digital computer. Generally, aprocessor will receive instructions and data from a read-only memory ora random-access memory or both. The essential elements of a computer area processor for executing instructions and one or more memory devicesfor storing instructions and data. Generally, a computer will alsoinclude, or be operatively coupled to receive data from or transfer datato, or both, one or more mass storage devices for storing data, e.g.,magnetic, magneto-optical disks, or optical disks. Information carrierssuitable for embodying computer program instructions and data includeall forms of non-volatile memory, including by way of example,semiconductor memory devices, (e.g., EPROM, EEPROM, and flash memorydevices); magnetic disks, (e.g., internal hard disks or removabledisks); magneto-optical disks; and optical disks (e.g., CD and DVDdisks). The processor and the memory can be supplemented by, orincorporated in, special purpose logic circuitry.

To provide for interaction with a user, the subject matter describedherein can be implemented on a computer having a display device, e.g., aCRT (cathode ray tube) or LCD (liquid crystal display) monitor, fordisplaying information to the user and a keyboard and a pointing device,(e.g., a mouse or a trackball), by which the user can provide input tothe computer. Other kinds of devices can be used to provide forinteraction with a user as well. For example, feedback provided to theuser can be any form of sensory feedback, (e.g., visual feedback,auditory feedback, or tactile feedback), and input from the user can bereceived in any form, including acoustic, speech, or tactile input.

The techniques described herein can be implemented using one or moremodules. As used herein, the term “module” refers to computing software,firmware, hardware, and/or various combinations thereof. At a minimum,however, modules are not to be interpreted as software that is notimplemented on hardware, firmware, or recorded on a non-transitoryprocessor readable recordable storage medium (i.e., modules are notsoftware per se). Indeed “module” is to be interpreted to always includeat least some physical, non-transitory hardware such as a part of aprocessor or computer. Two different modules can share the same physicalhardware (e.g., two different modules can use the same processor andnetwork interface). The modules described herein can be combined,integrated, separated, and/or duplicated to support variousapplications. Also, a function described herein as being performed at aparticular module can be performed at one or more other modules, and/orby one or more other devices, instead of or in addition to the functionperformed at the particular module. Further, the modules can beimplemented across multiple devices, and/or other components, local orremote to one another. Additionally, the modules can be moved from onedevice and added to another device, and/or can be included in bothdevices.

The subject matter described herein can be implemented in a computingsystem that includes a back-end component (e.g., a data server), amiddleware component (e.g., an application server), or a front-endcomponent (e.g., a client computer having a graphical user interface ora web interface through which a user can interact with an implementationof the subject matter described herein), or any combination of suchback-end, middleware, and front-end components. The components of thesystem can be interconnected by any form or medium of digital datacommunication, e.g., a communication network. Examples of communicationnetworks include a local area network (“LAN”) and a wide area network(“WAN”), e.g., the Internet.

Approximating language, as used herein throughout the specification andclaims, may be applied to modify any quantitative representation thatcould permissibly vary without resulting in a change in the basicfunction to which it is related. Accordingly, a value modified by a termor terms, such as “about” and “substantially,” are not to be limited tothe precise value specified. In at least some instances, theapproximating language may correspond to the precision of an instrumentfor measuring the value. Here and throughout the specification andclaims, range limitations may be combined and/or interchanged, suchranges are identified and include all the sub-ranges contained thereinunless context or language indicates otherwise.

What is claimed is:
 1. A method comprising: receiving datacharacterizing first signal diagnostics and data characterizing a firstspeed of a first acoustic signal through a gas mixture along a firstpath in a pipe, the first speed of the first acoustic signal detected bya first channel of an ultrasonic flow meter including a first pair oftransducers that are separated by a first path length of the first path,wherein the gas mixture is configured to flow along a flow path in thepipe; determining a status associated with the ultrasonic flow meterbased on the data characterizing the first signal diagnostics and/or adifference between the first speed of the first acoustic signal and aspeed of sound, wherein the speed of sound is calculated based on one ormore properties of the gas mixture; and providing a notificationincluding the determined status to a user and/or saving the notificationto an electronic storage.
 2. The method of claim 1, further comprising:receiving data characterizing the one or more properties of the gasmixture, the one or more properties includes one or more of compositionof the gas mixture, pressure of the gas mixture in the ultrasonic flowmeter, and temperature of the gas mixture; and calculating, using apredetermined algorithm, the speed of sound based on the datacharacterizing the one or more properties of the gas mixture.
 3. Themethod of claim 2, wherein the predetermined algorithm includes one ormore of a molecular-weight based algorithm, an AGA10 method and an idealgas law.
 4. The method of claim 1, wherein the status includes anidentity of the ultrasonic flow meter.
 5. The method of claim 1, whereinthe data characterizing the first signal diagnostics includes one ormore of the first path length, time delay of a first transducer and/or asecond transducer of the first pair of transducers and a signalstrength, and a signal-to-noise ratio, and wherein the datacharacterizing the first speed of the first acoustic signal includes afirst upstream time of travel of sound from the first transducer to thesecond transducer, and a first downstream time of travel of sound fromthe second transducer to the first transducer.
 6. The method of claim 5,further comprising receiving data characterizing second signaldiagnostics and data characterizing a second speed of a second acousticsignal through a gas mixture along a second path in the pipe, the secondspeed of the second acoustic signal detected by a second channel of theultrasonic flow meter including a second pair of transducers that areseparated by a second path length of the second path, wherein the datacharacterizing the second signal diagnostics includes one or more of thesecond path length, time delay of a third transducer and/or a fourthtransducer of the second pair of transducers, and a signal-to-noiseratio, and wherein the data characterizing the second speed of thesecond acoustic signal includes a second upstream time of travel ofsound from the third transducer to the fourth transducer, and a seconddownstream time of travel of sound from the fourth transducer to thethird transducer.
 7. The method of claim 6, wherein determining thestatus includes: determining that one or more of the first signaldiagnostics of the first acoustic signal has a first predeterminedvalue, the second signal diagnostics of the second acoustic signal has asecond predetermined value, the difference between the first speed ofthe first acoustic signal and the calculated speed of sound is above ahigher threshold value, and a difference between the second speed of thesecond acoustic signal and the calculated speed of sound is above thehigher threshold value; and setting the status associated with theultrasonic flow meter to indicate a maintenance request.
 8. The methodof claim 6, wherein determining the status includes: determining thatone or more of the first signal diagnostics of the first acoustic signalhas a first predetermined value, the second signal diagnostics of thesecond acoustic signal has a second predetermined value, the differencebetween the first speed of the first acoustic signal and the calculatedspeed of sound is below a higher threshold value and above a lowerthreshold value, and a difference between the second speed of the secondacoustic signal and the calculated speed of sound is below the higherthreshold value and above the lower threshold value; and setting thestatus associated with the ultrasonic flow meter to indicate that theultrasonic flow meter requires calibration.
 9. The method of claim 8,further comprising calibrating the ultrasonic flow meter by varying oneor more of time delay of the first transducer and/or the secondtransducer, the first path length, time delay of the third transducerand/or the fourth transducer, and the second path length.
 10. The methodof claim 6, wherein determining the status includes: determining thatone or more of the first signal diagnostics of the first acoustic signalhas a predetermined value, the difference between the first speed of thefirst acoustic signal and the calculated speed of sound is below a lowerthreshold value, and a difference between the second speed of the secondacoustic signal and the calculated speed of sound is below the lowerthreshold value; and setting the status associated with the ultrasonicflow meter to indicate that the ultrasonic flow meter performance hasbeen validated.
 11. The method of claim 6, wherein determining thestatus includes: calculating a first velocity of fluid flow based ontime difference between the first upstream time of travel and the firstdownstream time of travel; calculating a second velocity of fluid flowbased on time difference between the second upstream time of travel andthe second downstream time of travel; calculating a difference betweenthe first fluid velocity and the second fluid velocity is above a higherthreshold value; and setting the status associated with the ultrasonicflow meter to indicate a maintenance request.
 12. The method of claim 6,wherein determining the status includes: calculating a first velocity offluid flow based on time difference between the first upstream time oftravel and the first downstream time of travel; calculating a secondvelocity of fluid flow based on time difference between the secondupstream time of travel and the second downstream time of travel;calculating a difference between the first fluid velocity and the secondfluid velocity is below a lower threshold value; and setting the statusassociated with the ultrasonic flow meter to indicate a successful insitu validation.
 13. The method of claim 1, wherein the notificationincludes the determined status in a flare application or industrialprocess application.
 14. A system comprising: at least one dataprocessor; memory coupled to the at least one data processor, the memorystoring instructions to cause the at least one data processor to performoperations comprising: receiving data characterizing first signaldiagnostics and data characterizing a first speed of a first acousticsignal through a gas mixture along a first path in a pipe, the firstspeed of the first acoustic signal detected by a first channel of anultrasonic flow meter including a first pair of transducers that areseparated by a first path length of the first path, wherein the gasmixture is configured to flow along a flow path in the pipe; determininga status associated with the ultrasonic flow meter based on the datacharacterizing the first signal diagnostics and/or a difference betweenthe first speed of the first acoustic signal and a speed of sound,wherein the speed of sound is calculated based on one or more propertiesof the gas mixture; and providing a notification including thedetermined status to a user and/or saving the notification to anelectronic storage.
 15. The system of claim 14, wherein the operationsfurther comprising: receiving data characterizing the one or moreproperties of the gas mixture, the one or more properties includes oneor more of composition of the gas mixture, pressure of the gas mixturein the ultrasonic flow meter, and temperature of the gas mixture; andcalculating, using a predetermined algorithm, the speed of sound basedon the data characterizing the one or more properties of the gasmixture.
 16. The system of claim 14, wherein the data characterizing thefirst signal diagnostics includes one or more of the first path length,time delay of a first transducer and/or a second transducer of the firstpair of transducers and a signal strength, and a signal-to-noise ratio,and wherein the data characterizing the first speed of the firstacoustic signal includes a first upstream time of travel of sound fromthe first transducer to the second transducer, and a first downstreamtime of travel of sound from the second transducer to the firsttransducer.
 17. The system of claim 16, wherein the operations furthercomprising receiving data characterizing second signal diagnostics anddata characterizing a second speed of a second acoustic signal through agas mixture along a second path in the pipe, the second speed of thesecond acoustic signal detected by a second channel of the ultrasonicflow meter including a second pair of transducers that are separated bya second path length of the second path, wherein the data characterizingthe second signal diagnostics includes one or more of the second pathlength, time delay of a third transducer and/or a fourth transducer ofthe second pair of transducers, and a signal-to-noise ratio, and whereinthe data characterizing the second speed of the second acoustic signalincludes a second upstream time of travel of sound from the thirdtransducer to the fourth transducer, and a second downstream time oftravel of sound from the fourth transducer to the third transducer. 18.The system of claim 17, wherein determining the status includes:determining that one or more of the first signal diagnostics of thefirst acoustic signal has a first predetermined value, the second signaldiagnostics of the second acoustic signal has a second predeterminedvalue, the difference between the first speed of the first acousticsignal and the calculated speed of sound is above a higher thresholdvalue, and a difference between the second speed of the second acousticsignal and the calculated speed of sound is above the higher thresholdvalue; and setting the status associated with the ultrasonic flow meterto indicate a maintenance request.
 19. The system of claim 17, whereindetermining the status includes: determining that one or more of thefirst signal diagnostics of the first acoustic signal has a firstpredetermined value, the second signal diagnostics of the secondacoustic signal has a second predetermined value, the difference betweenthe first speed of the first acoustic signal and the calculated speed ofsound is below a higher threshold value and above a lower thresholdvalue, and a difference between the second speed of the second acousticsignal and the calculated speed of sound is below the higher thresholdvalue and above the lower threshold value; and setting the statusassociated with the ultrasonic flow meter to indicate that theultrasonic flow meter requires calibration.
 20. The system of claim 19,wherein the operations further comprising calibrating the ultrasonicflow meter by varying one or more of time delay of the first transducerand/or the second transducer, the first path length, time delay of thethird transducer and/or the fourth transducer, and the second pathlength.
 21. The method of claim 17, wherein determining the statusincludes: determining that one or more of the first signal diagnosticsof the first acoustic signal has a predetermined value, the differencebetween the first speed of the first acoustic signal and the calculatedspeed of sound is below a lower threshold value, and a differencebetween the second speed of the second acoustic signal and thecalculated speed of sound is below the lower threshold value; andsetting the status associated with the ultrasonic flow meter to indicatethat the ultrasonic flow meter performance has been validated.
 22. Themethod of claim 17, wherein determining the status includes: calculatinga first velocity of fluid flow based on time difference between thefirst upstream time of travel and the first downstream time of travel;calculating a second velocity of fluid flow based on time differencebetween the second upstream time of travel and the second downstreamtime of travel; calculating a difference between the first fluidvelocity and the second fluid velocity is above a higher thresholdvalue; and setting the status associated with the ultrasonic flow meterto indicate a maintenance request.
 23. The method of claim 17, whereindetermining the status includes: calculating a first velocity of fluidflow based on time difference between the first upstream time of traveland the first downstream time of travel; calculating a second velocityof fluid flow based on time difference between the second upstream timeof travel and the second downstream time of travel; calculating adifference between the first fluid velocity and the second fluidvelocity is below a lower threshold value; and setting the statusassociated with the ultrasonic flow meter to indicate a successful insitu validation.